Why Are Moths Attracted to Lights at Night?
Moths are not really attracted by the light itself. When a moth flies at night, it uses the moon as a beacon to guide it. By always keeping the light of the moon falling on its eyes at the same angle, a moth is able to fly a straight path.
Since the moon is far away, its light falls in much the same angle to the Earth for whatever distance the moth might fly. But nearby lights confuse the moth. When it tries to navigate by a streetlight instead of the moon, the moth is forced to fly in ever smaller circles until it is eventually drawn to the light itself.
Entomologists have found that moths are less attracted to artificial lights during the week of the full moon than they are during the new moon week, and this observation sparked yet another theory.
“People used to say you don’t capture many moths with UV lamps at the time of the full moon because they’re all flying towards the moon, but they can’t carry on their life cycles if they’re flying to the moon.”
And indeed, the notion has been proven incorrect. “A study done in Scandinavia found out that it’s not that they aren’t attracted to lights as much when the moon is bright, it’s that they aren’t as active during that time because the light doesn’t drop off as much at night,” he said. Usually, he explained, nightfall and darkness trigger moth activity.